Carrier 50CR installation instructions Troubleshooting Chart Cont’d, Head pressure too low

Table 7—Troubleshooting Chart (Cont’d)

SYMPTOM	CAUSE	REMEDY
Head pressure too low	Low refrigerant charge	Check for leaks, repair and recharge
	Restriction in liquid tube	Remove restriction
	(Cool) High Heat load	Check for source and eliminate
Excessive suction pressure	Reversing valve hung up or leaking internally	Replace valve
	Refrigerant overcharged	Recover excess refrigerant
	(Cool) Dirty air filter	Replace filter
	(Heat) Outdoor coil frosted	Move timer on control board to 30 minutes between
		defrost cycles
	Low refrigerant charge	Check for leaks, repair and recharge
Suction pressure too low	Metering device or low side restricted	Remove source of restriction
	(Cool) Insufficient coil airflow	Increase air quantity
		Check filter–replace if necessary
	(Cool) Temperature too low in conditioned area	Reset UI setting
	(Cool) Outdoor ambient below 55°F	Install low--ambient kit
	Filter drier restricted	Replace
Compressor runs but outdoor fan does not	NC (normally closed) contacts on defrost board	Check condition of relay on board
	open	Replace if necessary
	Blower wheel not secured to shaft	Properly tighten blower wheel to shaft
IFM does not run	Insufficient voltage at motor	Determine cause and correct
	Power connectors not properly sealed	Connectors should snap easily; do not force
	Water dripping into motor	Verify proper drip loops in connector wires
IFM operation is intermittent	Connectors not firmly sealed	Gently pull wires individually to be sure they are
		crimped into the housing

IFM-Indoor Fan Motor

50CR

31